BIOCHEMICAL AND GENETIC-STUDIES ON ALKALINE-PHOSPHATASE OF CERATITIS-CAPITATA

Two forms of alkaline phosphatase exist in the integument of the ''whi te pupae'' (wp) and dark pupae (dp) mutant strains of ceratitis capita ta, during transition from larvae to pupae. They were separated by DEA E-cellulose chromatography. Both isoenzymes have a molecular weight of approximately 180,000 and two pH optima, at 9.4 and at 11.0. The isoe nzymes of the ''dark pupae'' mutant catalyze the hydrolysis of phospho tyrosine and beta-glycerophosphate but not phosphoserine, phosphothreo nine, ATP, and AMP. In contrast, the isoenzymes of the white pupae mut ant hydrolyze all the substrates tested. The ALPase 1 of the dark pupa e mutant was inhibited by L-tyrosine, but L-phenylalanine had no effec t on either isoenzyme. The effects of divalent cations, EDTA, temperat ure, urea, and 2-mercaptoethanol were also investigated Electrophoreti c analysis did not reveal any variants of the larval and pupal isoenzy mes, but ALPase A, art adult stage-specific isoenzyme, was found to be polymorphic. The electrophoretic variants were shown to be controlled by three codominant alleles located on the third chromosome of Cerati tis capitata. Since we found no hybrid enzyme, we conclude that ALPase A is monomeric.